System and method for preseparation of fischer-tropsch products

Abstract

The application provides a system and method for Fischer-Tropsch product pre-separation, the system comprising a gas-liquid phase separation unit, a gas phase refining unit and a water-oil phase separation unit; the gas-liquid phase separation unit comprises a gas-liquid phase separation tank, which is coaxially provided with a gas-liquid flow guide and a baffle assembly from bottom to top; the gas-liquid flow guide comprises a cylindrical main body, which is provided with a feed inlet on the bottom surface, and the lower part of the cylinder wall is a grid structure; the baffle assembly comprises a fixed shaft and a baffle coaxially arranged with the cylindrical main body; the gas phase refining unit comprises a cyclone separator connected to the gas phase outlet of the gas-liquid phase separation tank; the water-oil phase separation unit comprises a water-oil phase separation tank connected to the liquid phase outlet of the gas-liquid phase separation unit and the gas phase refining unit. The method using the system is also provided. The system and method can be used for Fischer-Tropsch product pre-separation, can reduce the mutual entrainment of gas-liquid two phases in the Fischer-Tropsch product pre-separation process, and can improve the multi-phase separation efficiency and the purity of the separated product.

Description

Technical Field

[0001] This invention belongs to the field of material separation, and specifically relates to a system and method for the pre-separation of Fischer-Tropsch products. Background Technology

[0002] Fischer-Tropsch synthesis is a technique that converts syngas (CO and H2) into hydrocarbon organic compounds (mainly including alkanes and alkenes) through a specific catalyst. At the same time, a large amount of water and some oxygen-containing organic compounds (mainly alcohols, aldehydes, acids, etc.) are generated in the process, and a large amount of heat is released.

[0003] In most Fischer-Tropsch synthesis projects that have already commenced, the initial separation process of water and hydrocarbon products generated by the Fischer-Tropsch synthesis reaction involves: the products undergoing cooling flash evaporation, with most of the water and oil cooled into a liquid phase fluid. An oil-water separator separates an aqueous phase fluid (i.e., Fischer-Tropsch synthesis water) containing small amounts of hydrocarbons, oxygen-containing organic matter, and trace suspended solids from this liquid phase fluid. Due to the presence of hydrocarbons and oxygen-containing organic matter, Fischer-Tropsch synthesis water cannot be directly discharged. Separating and recycling the water from these oxygen-containing organic compounds can effectively improve the technical and economic efficiency of the Fischer-Tropsch synthesis process, enrich the Fischer-Tropsch synthesis products, reduce the environmental protection load on the aqueous phase, achieve water recycling, and enable clean production in the coal-to-oil process.

[0004] In actual production, the oil-water separation process varies greatly, and the separated Fischer-Tropsch synthesis water contains light oil and a small amount of suspended solids, resulting in poor operational stability of the downstream synthesis water treatment unit, affecting the Fischer-Tropsch synthesis water treatment effect, and consequently affecting the stable operation of the entire plant. Therefore, pretreatment before the Fischer-Tropsch synthesis water enters the downstream synthesis water treatment unit is particularly important to ensure the stable operation of the entire water treatment unit. Pretreatment can be used to separate the light oil, suspended solids, etc., carried in the Fischer-Tropsch synthesis water.

[0005] CN113135611A discloses an oil-water separation pretreatment device for Fischer-Tropsch synthesis water, equipment comprising the same, and a treatment method thereof. This device, by incorporating specific filter elements within the oil-water separation pretreatment device, effectively and simply separates heavy oil and small amounts of suspended solids from the water through interception and by utilizing the density difference between water and oil. The filter elements of the oil-water separation pretreatment device are backflushed according to the filtration pressure difference or the device's operating time to ensure the filter elements' interception effect on oil and suspended solids. Its core components include: a coalescing element for coalescing oil, and a vertically arranged U-shaped filter element; the filter element is prepared using one or more of organic polymer materials, metal mesh, and / or sintered metal powder, including filter bags, ceramic filters, metal mesh filters, candle filters, and / or sintered metal powder filters; the organic polymer materials include polyethylene, polypropylene, polyvinyl chloride, polyester, and / or polytetrafluoroethylene.

[0006] However, the following problems remain difficult to fully resolve: the actual separation effect of the aqueous and oil phases in Fischer-Tropsch synthesis is greatly affected by the catalyst and process, resulting in severe water-oil emulsification and mutual entrainment; low carbon number and volatile components are entrained in the gas phase, causing product loss; insufficient gas phase separation effect leads to heavy components being easily entrained in subsequent processes, causing pipeline blockage; the low efficiency of liquid phase product separation makes downstream processes more complex and product purity low; the separated Fischer-Tropsch synthesis water contains light oil and a small amount of suspended solids, affecting the stable operation of downstream synthesis water treatment units.

[0007] Therefore, the effectiveness of current pre-separation systems and methods for Fischer-Tropsch products needs to be improved, and more efficient methods are needed to achieve effective separation of the water, oil, and gas phases of Fischer-Tropsch products. Summary of the Invention

[0008] The first objective of this invention is to provide a system for the pre-separation of Fischer-Tropsch products, which can effectively reduce the mutual entrainment between the gas and liquid phases and improve the pre-separation effect of Fischer-Tropsch products.

[0009] The second objective of this invention is to provide a method for pre-separating Fischer-Tropsch products using the aforementioned system. This method enables the pre-separation of Fischer-Tropsch products and can effectively reduce the mutual entrainment between the gas and liquid phases, thereby improving the pre-separation effect of Fischer-Tropsch products.

[0010] To achieve the first objective of this invention, a system for the pre-separation of Fischer-Tropsch products is provided, the system comprising a gas-liquid phase separation unit, a gas-phase purification unit, and a water-oil phase separation unit; wherein,

[0011] The gas-liquid phase separation unit includes a gas-liquid phase separation tank for feeding Fischer-Tropsch products and separating them into gas and liquid phases, and outputting the gas phase from its top to the gas phase purification unit and the liquid phase from its bottom to the water-oil phase separation unit.

[0012] The gas-liquid phase separator is coaxially arranged with a gas-liquid guide and a baffle assembly from bottom to top.

[0013] The gas-liquid guide includes a cylindrical body; an inlet is provided on the bottom surface of the cylindrical body for feeding Fischer-Tropsch products; at least the lower part of the cylindrical wall of the cylindrical body is a grid structure for gas-liquid separation of the Fischer-Tropsch products entering therein, and the separated liquid phase is guided out from the grid structure to the gas-liquid phase separator.

[0014] The baffle assembly includes a fixed shaft and a baffle plate coaxially arranged with the cylindrical body, used to retain a portion of the gas phase separated from the Fischer-Tropsch products entering the gas-liquid guide as liquid.

[0015] The gas phase refining unit includes a cyclone separator connected to the gas phase outlet of the gas-liquid phase separation tank in the gas-liquid phase separation unit. The cyclone separator is used to receive the gas phase from the gas-liquid phase separation unit and perform cyclone separation on it, outputting the gas phase from its top and the liquid phase from its bottom.

[0016] The water-oil phase separation unit includes a water-oil phase separation tank, which is connected to the liquid phase outlet of the gas-liquid phase separation unit and the liquid phase outlet of the gas phase purification unit, respectively, for receiving the liquid phase from the gas-liquid phase separation unit and the liquid phase from the gas phase purification unit and separating the water and oil from them.

[0017] Preferably, in the gas-liquid phase separation unit, a first air hole is provided on the top surface of the cylindrical body. Multiple first air holes are distributed on the top surface of the cylindrical body, used for guiding and outputting a portion of the gas separated from the feed Fischer-Tropsch product and retaining the liquid; and / or

[0018] In the baffle assembly, there are n layers of baffles, where n≥1; the odd-numbered layers of baffles from bottom to top are coaxially and spaced apart on the fixed shaft, with a first gap between them and the inner wall of the gas-liquid phase separator for use as a gas passage; the even-numbered layers of baffles from bottom to top are coaxially and spaced apart on the inner wall of the gas-liquid phase separator, with a second gap between them and the fixed shaft for use as a gas passage.

[0019] Preferably, the baffle plate has a conical structure; more preferably, the cone angle of the baffle plate is 60-120°.

[0020] Preferably, the baffle plate has a second air hole on its surface, and there are multiple second air holes that are distributed on the surface of the baffle plate; preferably, the diameter of the second air hole is 1-3 mm.

[0021] Preferably, on the baffle plate, the total area of ​​the second air pore accounts for 0-20%;

[0022] Preferably, a liquid guiding groove is also provided on the surface of the baffle plate, with the first end of the liquid guiding groove located on the surface of the baffle plate and the last end located at the edge of the baffle plate, for guiding the liquid droplets condensed on the baffle plate to the bottom of the gas-liquid phase separator;

[0023] Preferably, the width of the liquid guiding groove is 2-5 mm; preferably, the depth of the liquid guiding groove is 1-5 mm.

[0024] Preferably, the liquid guiding channel includes a first liquid guiding channel, which is disposed from the center to the edge of the baffle plate; and / or

[0025] The liquid guiding channel includes a second liquid guiding channel, the first end of which is located at 1 / 3-2 / 3 of the distance from the center to the edge of the baffle plate.

[0026] Preferably, the height-to-diameter ratio of the gas-liquid phase separator is (1.5-4):1; and / or

[0027] The height ratio of the gas-liquid phase separator to the gas-liquid guide is (1.5-3):1; and / or

[0028] The diameter ratio of the gas-liquid phase separator to the gas-liquid guide is (1.5-5):1.

[0029] Preferably, the water-oil phase separator is provided with a water-oil separation chamber, and the bottom surface of the water-oil separation chamber is arranged to decrease sequentially from the feed end wall of the water-oil phase separator to its opposite end wall; the feed inlet of the water-oil separation chamber is connected to the liquid phase outlet of the gas-liquid phase separator and the liquid phase outlet of the gas phase purification unit, for feeding the liquid phase from the gas-liquid phase separator and the liquid phase from the gas phase purification unit;

[0030] The water-oil separation chamber is equipped with m-stage water-oil separation sub-units, where m ≥ 1, used to sequentially remove the oil phase from the liquid phase from the feed end to the opposite end; each water-oil separation sub-unit includes a coalescing oil absorption component, an oil collection component, and an oil conveying component; in the m-stage water-oil separation sub-units...

[0031] The coalescing oil absorption component is vertically arranged in the water-oil separation chamber, and is arranged sequentially from the feed end to the opposite end in the water-oil separation chamber, dividing the water-oil separation chamber into m water-oil separation sub-chambers and water chambers arranged sequentially from the feed end to the opposite end;

[0032] The oil conveying assembly is horizontally positioned at the upper part of the water-oil separation sub-chamber and is used to output the oil phase from the oil collecting assembly;

[0033] The oil collecting component is suspended below the oil conveying component and is flexibly connected to the oil conveying component, so as to float on the surface of the feed liquid phase;

[0034] The coalescing oil absorption component is used to output the aqueous phase after the liquid phase has been collected by the oil collection component and the residual oil phase is retained.

[0035] The water chamber is used to receive the aqueous phase output from the m-stage water-oil separation subunit;

[0036] Preferably, the oil collecting assembly includes a first oil collecting assembly in a horizontal direction and a second oil collecting assembly in a vertical direction. The first oil collecting assembly is horizontally floating on the surface of the feed liquid phase, and the two ends of the second oil collecting assembly are respectively connected to the first oil collecting assembly and the oil conveying assembly, for sequentially collecting the oil phase in the feed liquid phase.

[0037] Preferably, the bottom surface of the water-oil separation chamber is stepped down from the feed end wall of the water-oil phase separator to its opposite end wall.

[0038] Preferably, the bottom surfaces of the m water-oil separation sub-chambers and the water chamber are arranged in a stepped manner from the feed end wall of the water-oil phase separation tank to its opposite end wall;

[0039] Preferably, in two adjacent steps, the height of the step that is later is greater than the height of the step that is in front;

[0040] Preferably, in two adjacent steps, the ratio of the height of the step behind to the height of the step in front is 1-5.

[0041] Preferably, the coalescing oil-absorbing component is a frame-plate structure, including a support plate and an oil-absorbing layer. The oil-absorbing layer includes any one or more combinations of a coalescing material layer, an oil-absorbing cotton layer, and an oil-absorbing film layer. Preferably, the oil-absorbing layer has 1-6 layers. Preferably, the oil-absorbing layer has staggered channels for water molecules to pass through. Preferably, the diameter of the channels is 0.1-2 mm. Preferably, the total area of ​​the channels in each oil-absorbing layer accounts for 5-20% of the total area.

[0042] The second oil collection component is made of oil-absorbing cotton and / or elastic oil-absorbing gel; and / or

[0043] In the oil-water separation subunit, the ratio of the length of the second oil collecting component to the vertical length of the coalescing oil absorption component is 10-100%; and / or

[0044] The thickness of the first oil collection component is 2-50mm.

[0045] Preferably, the water-oil phase separation unit further includes an oil tank, which is connected to the outlet of the oil conveying assembly for receiving the oil phase from the oil conveying assembly;

[0046] Preferably, the water-oil phase separation unit further includes a second hydrocyclone, which is connected to the bottom outlet of the oil tank for extracting the water phase deposited at the bottom of the oil tank and separating it by hydrocyclone, outputting the oil phase from the top and the water phase from the bottom;

[0047] Preferably, the water-oil phase separation unit further includes an oil suction pump, which is installed on the oil pipeline from the oil conveying assembly to the oil tank, and is used to draw the oil phase from the oil conveying assembly;

[0048] Preferably, the water-oil separation tank is further provided with an equipment room, which is located below the water-oil separation chamber, and the oil tank and / or the second hydrocyclone is located in the equipment room.

[0049] Preferably, the gas-phase purification unit further includes a first hydrocyclone connected to the liquid phase outlet of the cyclone separator, for receiving the liquid phase from the cyclone separator and performing hydrocyclone separation on it, outputting the gas phase from its top and the liquid phase from its bottom; and / or

[0050] The gas phase purification unit further includes a filter, which is connected to the gas phase outlet of the cyclone separator and / or the gas phase outlet of the first cyclone separator, respectively, for filtering the gas phase from the cyclone separator and / or the gas phase from the first cyclone separator before outputting it.

[0051] To achieve the second objective of the present invention, a method for pre-separating Fischer-Tropsch products using the aforementioned system is provided.

[0052] Preferably, the method includes the following steps:

[0053] (1) The Fischer-Tropsch product is transported to the gas-liquid guide in the gas-liquid phase separation unit and guided out to the gas-liquid phase separation tank through the grid structure on the cylindrical main body wall; then the liquid phase entrained in the gas phase is intercepted in sequence by the gas-liquid guide and the baffle assembly, and the gas phase is output from the top of the gas-liquid phase separation tank and the liquid phase is output from the bottom of the gas-liquid phase separation tank.

[0054] (2) The gas phase output from the gas-liquid phase separation unit is sent to the gas phase purification unit, where it is separated by the cyclone separator. The gas phase is output from the top and the liquid phase is output from the bottom.

[0055] (3) The liquid phase output from the gas-liquid phase separation unit and the liquid phase output from the gas phase refining unit are sent to the water-oil phase separation unit, and water and oil are separated by the water-oil phase separation tank, and water phase and oil phase are output respectively.

[0056] The beneficial effects of this invention are as follows:

[0057] The system and method for pre-separation of Fischer-Tropsch products of the present invention can be used for pre-separation of Fischer-Tropsch products, and the multiphase separation effect is significantly improved. It reduces the water and oil entrained in the gas phase, reduces the oil content in the aqueous phase, reduces the water content in the oil phase, and improves the purity of products in subsequent processes. It also reduces the temperature of each stage of the system, reduces energy consumption, increases the driving force for two-phase separation, reduces the load on the coalescence oil absorption component, improves the permeation flux, and has high efficiency.

[0058] The water-oil phase separation unit adopts a box-type structure with a spacious upper part, which facilitates monitoring of the unit's operation and timely maintenance and process adjustments.

[0059] The coalescence oil absorption module adopts a plate and frame design, which facilitates the observation and sampling of coalescence and membrane module status;

[0060] The coalescing oil absorption component, oil collection component, and oil delivery component are independent of each other, simple to assemble, and easy to maintain and replace each component;

[0061] The oil collection components use flexible connections, and the second oil collection component in the vertical direction uses flexible, highly elastic oil-absorbing cotton / oil-absorbing gel and other materials, which can fully adapt to changes in liquid level.

[0062] By combining small-volume equipment such as gas-liquid phase separation units and cyclone separators, the pre-separation effect of gas and liquid phases, as well as water and oil phases in the liquid phase, is significantly improved, reducing the burden on subsequent processes.

[0063] It can reduce the mutual entrainment of gas and liquid phases, as well as water and oil phases in the liquid phase, during the pre-separation of Fischer-Tropsch products, thereby improving the three-phase separation efficiency and purity of the separated products; further reducing product loss and avoiding pipeline blockage in subsequent processes, which helps the downstream synthetic water treatment unit and the entire plant to operate stably; the equipment has a small footprint and low cost. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the system for pre-separation of Fischer-Tropsch products according to one embodiment of the present invention;

[0065] Figure 2 This is a schematic diagram of the gas-liquid guide in one embodiment of the system for pre-separation of Fischer-Tropsch products according to the present invention;

[0066] Figure 3 This is a top view of the uppermost baffle in one embodiment of the system for pre-separation of Fischer-Tropsch products according to the present invention. Detailed Implementation

[0067] The technical solution and its effects of the present invention will be further described below with reference to specific embodiments / examples. The following embodiments / examples are only for illustrating the content of the present invention, and the invention is not limited to the following embodiments or examples. Simple modifications made to the present invention based on the concept of the present invention are all within the scope of protection claimed by the present invention.

[0068] This invention provides a system for the pre-separation of Fischer-Tropsch products, such as... Figure 1-3 As shown, the system includes a gas-liquid phase separation unit 1, a gas phase purification unit 2, and a water-oil phase separation unit 3; wherein,

[0069] The gas-liquid phase separation unit 1 includes a gas-liquid phase separation tank 4, which is used to feed Fischer-Tropsch products and perform gas-liquid separation on them, and outputs the gas phase from its top to the gas phase purification unit 2, and outputs the liquid phase from its bottom to the water-oil phase separation unit 3.

[0070] The gas-liquid phase separator 4 is coaxially arranged with a gas-liquid guide 5 and a baffle assembly 6 from bottom to top.

[0071] The gas-liquid guide 5 includes a cylindrical body 51; the bottom surface of the cylindrical body 51 is provided with a feed inlet for feeding Fischer-Tropsch products; at least the lower part of the cylindrical wall of the cylindrical body 51 is a grid structure for gas-liquid separation of the Fischer-Tropsch products entering it, and the separated liquid phase is guided out from the grid structure to the gas-liquid phase separator 4.

[0072] The baffle assembly 6 includes a fixed shaft 61 and a baffle 62 coaxially arranged with the cylindrical body 51, which are used to retain a portion of the gas phase separated from the Fischer-Tropsch products entering the gas-liquid guide 5 as liquid.

[0073] The gas phase refining unit 2 includes a cyclone separator 21, which is connected to the gas phase outlet of the gas-liquid phase separation tank 4 in the gas-liquid phase separation unit 1. It is used to receive the gas phase from the gas-liquid phase separation unit 1 and perform cyclone separation on it, outputting the gas phase from its top and the liquid phase from its bottom.

[0074] The water-oil separation unit 3 includes a water-oil separation tank 7, which is connected to the liquid phase outlet of the gas-liquid separation unit 1 and the liquid phase outlet of the gas phase purification unit 2, respectively, and is used to receive the liquid phase from the gas-liquid separation unit 1 and the liquid phase from the gas phase purification unit 2 and separate them into water and oil.

[0075] The system for pre-separation of Fischer-Tropsch products of the present invention primarily aims to perform preliminary separation of the gas, oil, and water phases in the Fischer-Tropsch products, laying the groundwork for subsequent processing. Those skilled in the art will understand that the composition of the Fischer-Tropsch products entering the system includes: ① a gas phase containing permanent gases such as H2, CO, CO2, and CH4, as well as low-carbon hydrocarbons; ② an oil phase containing alkanes, alkenes, and higher-carbon oxygen-containing compounds; and ③ an aqueous phase containing lower-carbon oxygen-containing compounds. The gas phase easily entrains small droplets from the oil and water phases, and due to temperature and pressure changes during the process, phase changes such as flash evaporation can easily occur, further exacerbating mist entrainment. The oil and water phases are prone to emulsification and entrainment, resulting in small droplets of water-in-oil and oil-in-water distributed in both phases, leading to incomplete separation and significantly adversely affecting subsequent processes.

[0076] In the system for pre-separation of Fischer-Tropsch products of the present invention, at least the lower part of the cylindrical body 51 of the gas-liquid guide 5 is configured as a grid structure, which helps to break up the Fischer-Tropsch products, thereby releasing the gas phase therein. This also increases the gas phase path and the contact area of ​​the gas phase within the system, thus achieving preliminary separation of the gas and liquid phases in the Fischer-Tropsch products. The separated liquid phase is guided out through the grid structure to the gas-liquid phase separator 4, while the separated gas phase rises. The different arrangement of odd-numbered and even-numbered baffles in the baffle assembly 6 from bottom to top helps to increase the gas phase path and the contact area of ​​the gas phase within the system, thereby further promoting gas-liquid separation and reducing mist entrainment in the gas phase. The specific arrangement of the gas-liquid guide 5 and the baffle assembly 6 effectively reduces gas phase turbulence, increases the gas phase path and the contact area of ​​the gas phase within the system, thereby effectively promoting gas-liquid separation.

[0077] The system for pre-separation of Fischer-Tropsch products of the present invention can be used for pre-separation of Fischer-Tropsch products. Through the arrangement of various structures, it can be broken down into smaller parts. First, a small gas-liquid phase separation unit 1 is used to perform preliminary separation of the gas phase. The gas-liquid guide 5 and the baffle assembly 6 increase the airflow path and the contact area within the gas-liquid phase separation unit 1, thereby reducing the liquid phase entrained in the gas phase. The gas phase output from the gas-liquid phase separation unit 1 then enters the cyclone separator 21 in the gas phase purification unit 2. The cyclone separator 21 is driven by the pressure difference before and after, further blocking the liquid droplets entrained in the gas phase, thereby reducing the mutual entrainment of the gas and liquid phases during the pre-separation of Fischer-Tropsch products. Furthermore, the water-oil separation unit can further separate the liquid phase into water and oil. This improves the multiphase (gas, water, and oil) separation efficiency and the purity of the separated products. Moreover, due to the improved separation effect, the operating temperature of each stage of the separation system can be reduced, thus reducing energy consumption.

[0078] Those skilled in the art will understand that the Fischer-Tropsch product may be derived from Fischer-Tropsch synthesis reactor 1'.

[0079] Those skilled in the art will understand that the baffle 62 can be replaced by a fine mesh.

[0080] In one embodiment, in the gas-liquid phase separation unit 1, a first air hole 52 is provided on the top surface of the cylindrical body 51. Multiple first air holes 52 are distributed dispersedly on the top surface of the cylindrical body 51, preferably uniformly, for guiding and outputting a portion of the gas separated from the feed Fischer-Tropsch product and retaining the liquid; and / or

[0081] In the baffle assembly 6, the baffle 62 has n layers, n≥1, such as 1, 2, 3, 4, 5, etc.; the odd-numbered layers of baffles from bottom to top are coaxially and spaced apart on the fixed shaft 61, and a first gap is left between them and the inner wall of the gas-liquid phase separator 4 to serve as a gas passage; the even-numbered layers of baffles from bottom to top are coaxially and spaced apart on the inner wall of the gas-liquid phase separator 4, and a second gap is left between them and the fixed shaft to serve as a gas passage.

[0082] The placement of the first pore helps to break up the foam of the Fischer-Tropsch product, thereby releasing the gas phase therein; the specific arrangement of the first pore and the baffle assembly helps to further increase the gas phase path and the contact area of ​​the gas phase in the system, thereby achieving the initial separation of the gas and liquid phases in the Fischer-Tropsch product.

[0083] In one embodiment, the baffle 62 has a conical structure; preferably, the cone angle of the baffle 62 is 60-120°, such as 65°, 70°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 110° and 115°.

[0084] Those skilled in the art will understand that the baffle plate 62 can also be other structures. In one embodiment, the baffle plate 62 is an N-shaped pyramidal structure, where N≥3, such as a triangular pyramidal structure, a quadrangular pyramidal structure, a pentagonal pyramidal structure, etc.

[0085] To further reduce liquid entrainment in the gas phase and trap liquid in the gas phase, in one embodiment, the baffle plate 62 is provided with a second vent 621 on its surface. There are multiple second vents 621, which are dispersed on the surface of the baffle plate 62, preferably uniformly dispersed. Preferably, the diameter of the second vents 621 is 1-3 mm, such as 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, or 1.9 mm. The diameters are 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, and 2.9 mm; preferably, the proportion of the total area of ​​the second air hole 621 on the baffle plate 62 is 0-20%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, and 19%.

[0086] To facilitate the rapid and convenient diversion of the trapped liquid phase to the gas-liquid phase separator 4, in one embodiment, a liquid guiding groove is also provided on the surface of the baffle plate 62. The first end of the liquid guiding groove is located on the surface of the baffle plate 62, and the second end is located at the edge of the baffle plate 62, which is used to guide the liquid droplets condensed on the baffle plate 62 to the bottom of the gas-liquid phase separator 4. Preferably, the width of the liquid guiding groove is 2-5mm, such as 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4.0mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, and 4.9mm; preferably, the depth of the liquid guiding groove is 1-5mm, such as 1.1mm, 1... .2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm, 3.0mm, 3.1mm, 3.2mm, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm, 4.0mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm and 4.9mm.

[0087] To accelerate the flow of the liquid phase trapped by the baffle plate 62 to the gas-liquid phase separator 4, in one embodiment, the liquid guiding channel includes a first liquid guiding channel 622, which extends from the center to the edge of the baffle plate 62, i.e., the first end of the first liquid guiding channel 622 is located at the center of the baffle plate 62, and the last end is located at the edge of the baffle plate 62; preferably, the first liquid guiding channel 622 is arranged along the generatrix of the baffle plate 62; and / or

[0088] The liquid guiding channel includes a second liquid guiding channel 623. The first end of the second liquid guiding channel 623 is located at 1 / 3 to 2 / 3 of the distance from the center to the edge of the baffle plate 62, such as 4 / 9, 1 / 2, or 5 / 9. That is, the first end of the second liquid guiding channel 623 is located at 1 / 3 to 2 / 3 of the distance from the center to the edge of the baffle plate 62, and the end is located at the edge of the baffle plate 62.

[0089] In one embodiment, the liquid guiding groove is disposed on the upper surface of the baffle plate 62.

[0090] In one embodiment, the height-to-diameter ratio of the gas-liquid phase separator 4 is (1.5-4):1, such as 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3.0:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, and 3.9:1; and / or

[0091] The height ratio of the gas-liquid phase separator 4 to the gas-liquid guide 5 is (1.5-3):1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, and 2.9:1; and / or

[0092] The diameter ratio of the gas-liquid phase separator 4 to the gas-liquid guide 5 is (1.5-5):1, for example, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3.0:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4.0:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, and 4.9:1.

[0093] In one embodiment, the water-oil separation tank 7 is provided with a water-oil separation chamber 8. The bottom surface of the water-oil separation chamber 8 is arranged to decrease sequentially from the feed end wall of the water-oil separation tank 7 to its opposite end wall. The feed inlet of the water-oil separation chamber 8 is connected to the liquid phase outlet of the gas-liquid separation unit 1 and the liquid phase outlet of the gas phase purification unit 2, and is used to feed the liquid phase from the gas-liquid separation unit 1 and the liquid phase from the gas phase purification unit 2.

[0094] The water-oil separation chamber 8 is equipped with m-stage water-oil separation sub-units, where m ≥ 1, such as 1, 2, 3, 4, 5, 6, etc., used to sequentially remove the oil phase from the liquid phase from the feed end to the opposite end; each water-oil separation sub-unit includes a coalescence oil absorption component 81, an oil collection component 82, and an oil conveying component 83; in the m-stage water-oil separation sub-units,

[0095] The coalescing oil absorption component 81 is vertically arranged in the water-oil separation chamber 8, and is arranged sequentially from the feed end to the opposite end in the water-oil separation chamber 8, dividing the water-oil separation chamber 8 into m water-oil separation sub-chambers 9 and water chambers 10 arranged sequentially from the feed end to the opposite end;

[0096] The oil conveying assembly 83 is horizontally disposed in the upper part of the water-oil separation sub-chamber 9, and is used to output the oil phase from the oil collecting assembly 82;

[0097] The oil collecting component 82 is suspended below the oil conveying component 83 and is flexibly connected to the oil conveying component 83, and is used to float on the surface of the feed liquid phase;

[0098] The coalescing oil absorption component 81 is used to output the aqueous phase after the liquid phase has been collected by the oil collection component 82 and the residual oil phase is intercepted.

[0099] The water chamber 10 is used to receive the aqueous phase output from the m-stage water-oil separation subunit;

[0100] Preferably, the oil collecting assembly 82 includes a first oil collecting assembly 821 in a horizontal direction and a second oil collecting assembly 822 in a vertical direction. The first oil collecting assembly 821 is horizontally floating on the surface of the feed liquid phase. The two ends of the second oil collecting assembly 822 are respectively connected to the first oil collecting assembly 821 and the oil conveying assembly 83, for sequentially collecting the oil phase in the feed liquid phase.

[0101] Those skilled in the art will understand that water and oil phases have a density difference, with the water phase having a higher density and the oil phase having a lower density; therefore, the oil phase is located above the water phase. This invention, through a water-oil phase separation unit, utilizes the oil collecting component 82 and the oil conveying component 83 to extract and output the oil phase from the liquid phase from the top using self-suction or external suction. Furthermore, the coalescing oil-absorbing component 81 ensures the oil phase is thoroughly separated from the liquid phase through stepwise coalescence, and then output via the oil collecting component 82 and the oil conveying component 83. This significantly increases the height range of the oil phase, fully utilizes the density difference between the water and oil phases, and makes the oil phase separation more precise and thorough. This helps reduce the difficulty of subsequent processing of the oil and water phases and improves product purity. The coalescing oil-absorbing component 81, the oil collecting component 82, and the oil conveying component 83 in the water-oil phase separation unit 3 are independent of each other, simple to assemble, and easy to maintain and replace each component.

[0102] The oil collecting component 82 and the oil conveying component 83 are connected by a flexible connection. The first oil collecting component 821 in the horizontal direction floats on the water surface and adsorbs and collects oil molecules in real time, greatly reducing the load on the coalescing oil absorption component located behind it. The second oil collecting component 822 in the vertical direction is made of flexible and highly elastic oil-absorbing cotton / oil-absorbing gel and other materials, and is connected between the oil conveying component 83 and the oil collecting component 82. The oil conveying component 83 delivers the oil phase in the oil collecting component 82 in real time. After the liquid phase passes through each stage of coalescing oil absorption component 81, the residual oil phase is efficiently intercepted step by step, and the liquid level drops step by step. The oil collecting component 82 can fully adapt to the liquid level change.

[0103] In the water-oil phase separation unit, the bottom of the water-oil separation chamber 8 is set to decrease sequentially, so the water phase liquid level decreases step by step, the water phase is vertically downward and the oil phase is vertically upward for separation, which increases the driving force for the separation of the two phases, reduces the load on the coalescence oil absorption component, improves the permeation flux, and has high separation efficiency.

[0104] The water-oil phase separation unit has a box-type structure with a spacious upper part, which facilitates monitoring of the unit's operation and timely maintenance and process adjustments.

[0105] This invention, through the setting of a water-oil separation unit, can further separate water and oil in the liquid phase, improve the separation efficiency of the water and oil phases and the purity of the products separated by subsequent units; and due to the improved separation effect, the operating temperature of each stage of the separation system can be reduced, thus reducing energy consumption.

[0106] In one embodiment, the bottom surface of the water-oil separation chamber 8 is set in a stepped manner from the feed end wall of the water-oil phase separation box 7 to its opposite end wall.

[0107] Preferably, the bottom surfaces of the m water-oil separation sub-chambers 9 and the water chamber 10 are arranged in a stepped manner from the feed end wall of the water-oil phase separation tank 7 to its opposite end wall;

[0108] Preferably, in two adjacent steps, the height of the step that is later is greater than the height of the step that is in front;

[0109] Preferably, in two adjacent steps, the ratio of the height of the step behind to the height of the step in front is 1-5, such as 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, and 5.0.

[0110] In one embodiment, the coalescing oil-absorbing component 81 has a frame-plate structure, including a support plate and an oil-absorbing layer. The oil-absorbing layer includes any one or more combinations of a coalescing material layer, an oil-absorbing cotton layer, and an oil-absorbing film layer. Preferably, the oil-absorbing layer has 1-6 layers, such as 3, 4, or 5 layers. Preferably, the oil-absorbing layer has staggered channels for water molecules to pass through. Preferably, the diameter of the channels is 0.1-2 mm, such as 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, or 0. 7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, and 2.0mm; preferably, in each oil-absorbing layer, the total area of ​​the channels accounts for 5-20%, such as 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, and 20%; and / or

[0111] The second oil collection component 822 is made of oil-absorbing cotton and / or elastic oil-absorbing gel; and / or

[0112] In the oil-water separation subunit, the ratio of the length of the second oil collecting component 822 to the vertical length of the coalescing oil absorption component 81 is 10-100%, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, and 100%; and / or

[0113] The thickness of the first oil collecting component 821 is 2-50mm, such as 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm, 34mm, 36mm, 38mm, 40mm, 42mm, 44mm, 46mm, 48mm and 50mm.

[0114] Those skilled in the art will understand that the length of the second oil collecting component 822 refers to its length in the vertical direction; and the thickness of the first oil collecting component 821 refers to its vertical thickness, that is, its thickness in the vertical direction.

[0115] In this invention, the coalescence oil absorption assembly installed in the water-oil separation chamber 8 of the water-oil phase separation box 7 adopts a plate and frame type, which makes it easy to observe and sample the coalescence and membrane assembly status.

[0116] In one embodiment, the water-oil phase separation unit 3 further includes an oil tank 11, which is connected to the outlet of the oil conveying assembly 83 and is used to receive the oil phase from the oil conveying assembly 83.

[0117] Preferably, the water-oil phase separation unit 3 further includes a second hydrocyclone 12, which is connected to the bottom outlet of the oil tank 11 and is used to extract the water phase deposited at the bottom of the oil tank 11 and perform hydrocyclone separation on it, outputting the oil phase from the top and the water phase from the bottom.

[0118] When the oil phase has a high density and viscosity, a pump or similar device can be installed between the oil conveying assembly and the oil tank for auxiliary suction. In one embodiment, the water-oil phase separation unit 3 further includes an oil suction pump, which is installed on the oil pipeline from the oil conveying assembly 83 to the oil tank 11, and is used to suction the oil phase in the oil conveying assembly 83.

[0119] To save space, in one embodiment, an equipment room 13 is also provided inside the water-oil separation tank 7. The equipment room 13 is located below the water-oil separation chamber 8, and the oil tank 11 and / or the second hydrocyclone 12 are located inside the equipment room 13.

[0120] In one embodiment, the gas-phase purification unit 2 further includes a first hydrocyclone 22 connected to the liquid phase outlet of the cyclone separator 21, for receiving the liquid phase from the cyclone separator 21 and performing hydrocyclone separation on it, outputting the gas phase from its top and the liquid phase from its bottom; and / or

[0121] The gas phase purification unit 2 further includes a filter 23, which is connected to the gas phase outlet of the cyclone separator 21 and / or the gas phase outlet of the first hydrocyclone 22, respectively, for filtering the gas phase from the cyclone separator 21 and / or the gas phase from the first hydrocyclone 22 before outputting it; preferably, the filter 23 is filled with absorbent materials such as oil-absorbing cotton / water-absorbing silica gel.

[0122] In this invention, the first hydrocyclone 22 can separate the gas phase from the liquid phase by cyclone separation, further improving the gas-liquid separation efficiency, gas-liquid separation effect and separation product purity; the filter 23 can further filter and retain the liquid phase (such as oil and water) in the gas phase, significantly improving the pre-separation effect of the gas and liquid phases and reducing the burden on subsequent steps.

[0123] The system for pre-separation of Fischer-Tropsch products of the present invention achieves high-level separation of the three phases of gas, oil, and water by sequentially utilizing a gas-liquid phase separation unit, a gas phase purification unit, and a water-oil phase separation unit; and further efficiently separates and recovers the liquid phase in the gas phase by using components such as cyclone separators, hydrocyclones, and filters; and achieves vertical separation of the oil phase vertically upward and the water phase vertically downward by setting the bottom surface of the water-oil separation chamber and its internal coalescing oil absorption component, oil collection component, and oil conveying component in the water-oil phase separation unit, thereby increasing the driving force for the two-phase separation, reducing the load on the coalescing oil absorption component, improving the permeation flux, and achieving high separation efficiency.

[0124] The present invention also provides a method for pre-separating Fischer-Tropsch products using the aforementioned system.

[0125] In one implementation, the method includes the following steps:

[0126] (1) The Fischer-Tropsch product is transported to the gas-liquid guide 5 in the gas-liquid phase separation unit 1, and then guided out to the gas-liquid phase separation tank 4 through the grid structure on the cylindrical body 51; then the liquid phase entrained in the gas phase is intercepted in sequence by the gas-liquid guide 5 and the baffle assembly 6, and the gas phase is output from the top of the gas-liquid phase separation tank 4 and the liquid phase is output from the bottom of the gas-liquid phase separation tank 4.

[0127] (2) The gas phase output from the gas-liquid phase separation unit 1 is sent to the gas phase purification unit 2, and the gas phase is separated by the cyclone separator 21. The gas phase is output from the top and the liquid phase is output from the bottom.

[0128] (3) The liquid phase output from the gas-liquid phase separation unit 1 and the liquid phase output from the gas phase purification unit 2 are sent to the water-oil phase separation unit 3, and water and oil are separated by the water-oil phase separation tank 7, and water phase and oil phase are output respectively.

[0129] In one embodiment, the method further includes:

[0130] In step (1), the liquid phase from the cyclone separator 21 is sent to the first hydrocyclone 22 for cyclone separation, and the gas phase is output from the top and the liquid phase is output from the bottom.

[0131] Preferably, the method further includes:

[0132] In step (1), the gas phase from the cyclone separator 21 and / or the gas phase from the first cyclone separator 22 are sent to the filter 23 for filtration and then output.

[0133] In one embodiment, the method further includes:

[0134] In step (3), the oil phase from the oil delivery assembly 83 is delivered to the oil tank 11;

[0135] Preferably, the method further includes:

[0136] In step (3), the second hydrocyclone 12 is used to extract the water phase deposited at the bottom of the oil tank 11 and to separate it by hydrocyclone separation, outputting the oil phase from the top and the water phase from the bottom.

[0137] The present invention will be further illustrated below with specific embodiments and comparative examples.

[0138] Examples 1-4 (S1-4) and Comparative Examples 1-2 (D1-2)

[0139] Utilize Figure 1-3 The system shown pre-separates Fischer-Tropsch products; wherein,

[0140] The system includes a gas-liquid phase separation unit 1, a gas phase purification unit 2, and a water-oil phase separation unit 3;

[0141] The gas-liquid phase separation unit 1 includes a gas-liquid phase separation tank 4, and a gas-liquid flow guide 5 and a baffle assembly 6 are coaxially arranged from bottom to top in the gas-liquid phase separation tank 4.

[0142] The gas-liquid guide 5 includes a cylindrical body 51; a feed inlet is provided on the bottom surface of the cylindrical body 51; at least the lower part of the cylindrical wall of the cylindrical body 51 is a grid structure;

[0143] The baffle assembly 6 includes a fixed shaft 61 and baffles 62 coaxially arranged with the cylindrical body 51; the baffles 62 have n layers, n≥1; the odd-numbered layers of baffles from bottom to top are sequentially and coaxially fixed to the fixed shaft 61, and a first gap is left between them and the inner wall of the gas-liquid phase separator 4 to serve as a gas passage; the even-numbered layers of baffles from bottom to top are sequentially and coaxially fixed to the inner wall of the gas-liquid phase separator 4, and a second gap is left between them and the fixed shaft to serve as a gas passage; the baffles 62 have a conical structure; the cone angle of the baffles 62 is 90°;

[0144] The gas phase refining unit 2 includes a cyclone separator 21, which is connected to the gas phase outlet of the gas-liquid phase separation tank 4 in the gas-liquid phase separation unit 1.

[0145] The water-oil phase separation unit 3 includes a water-oil phase separation tank 7, which is connected to the liquid phase outlet of the gas-liquid phase separation unit 1 and the liquid phase outlet of the gas phase purification unit 2, respectively.

[0146] The water-oil separation tank 7 is provided with a water-oil separation chamber 8. The bottom surface of the water-oil separation chamber 8 is arranged to decrease sequentially from the feed end wall of the water-oil separation tank 7 to its opposite end wall. The feed inlet of the water-oil separation chamber 8 is connected to the liquid phase outlet of the gas-liquid separation unit 1 and the liquid phase outlet of the gas phase purification unit 2.

[0147] The water-oil separation chamber 8 is equipped with m-stage water-oil separation sub-units, where m ≥ 1; each water-oil separation sub-unit includes a coalescing oil absorption component 81, an oil collection component 82, and an oil conveying component 83; in the m-stage water-oil separation sub-units...

[0148] The coalescing oil absorption component 81 is vertically arranged in the water-oil separation chamber 8, and is arranged sequentially from the feed end to the opposite end in the water-oil separation chamber 8, dividing the water-oil separation chamber 8 into m water-oil separation sub-chambers 9 and water chambers 10 arranged sequentially from the feed end to the opposite end;

[0149] The oil conveying assembly 83 is horizontally disposed in the upper part of the water-oil separation sub-chamber 9, and is used to output the oil phase from the oil collecting assembly 82;

[0150] The oil collecting component 82 is suspended below the oil conveying component 83 and is flexibly connected to the oil conveying component 83, and is used to float on the surface of the feed liquid phase;

[0151] The coalescing oil absorption component 81 is used to output the aqueous phase after the liquid phase has been collected by the oil collection component 82 and the residual oil phase is intercepted.

[0152] The water chamber 10 is used to receive the aqueous phase output from the m-stage water-oil separation subunit;

[0153] The oil collecting assembly 82 includes a horizontal first oil collecting assembly 821 and a vertical second oil collecting assembly 822. The first oil collecting assembly 821 is horizontally floating on the surface of the feed liquid phase. The two ends of the second oil collecting assembly 822 are respectively connected to the first oil collecting assembly 821 and the oil conveying assembly 83, for sequentially collecting the oil phase in the feed liquid phase. The differences between the systems in S1-4 and D1-2 are only shown in Table 1.

[0154] The Fischer-Tropsch products were pre-separated using the aforementioned system and the method of the present invention. The separation results are shown in Table 1.

[0155] Table 1. Differences and Separation Effects of Systems S1-4 and D1-2 Used for Pre-Separation of Fischer-Tropsch Products

[0156]

[0157] Note: " / " in the table indicates no or no; n=0 means no baffle, excluding the specific settings of the baffle assembly; m=0 means the water-oil separation subunit is 0, excluding the specific settings of the water-oil separation subunit.

[0158] Based on the comparison of Examples 1-4 and Comparative Examples 1-2, and the data in Table 1, it can be seen that the system and method of the present invention have a low system temperature, can be carried out at room temperature and pressure, have good phase separation effect, and the phase separation products have a low gas phase entrainment rate, low oil content in the aqueous phase, and low water content in the oil phase.

[0159] Based on the comparison of Comparative Examples 1 and 2, it can be seen that the phase separation effect of Comparative Example 1 is poor. In the phase separation products, the gas phase entrainment rate is high, the water phase has a high oil content, and the oil phase has a high water content, with severe mutual entrainment among the phases. Compared with Comparative Example 1, although Comparative Example 2 has three layers of baffles, which slightly reduces the gas phase entrainment rate, water phase oil content, and oil phase water content, the effect is not significant.

[0160] A comparison of Example 1 and Comparative Example 2 shows that, compared to Comparative Example 2, Example 1, with its three-layer baffles all fixed on the fixed shaft 61, incorporates a grid structure on the lower part of the cylindrical body 51 in the gas-liquid guide, which helps to break up the Fischer-Tropsch product and release the gas phase. Furthermore, a cyclone separator 21 in the gas phase refining unit 2 is also included, further blocking liquid droplets entrained in the gas phase. This reduces the amount of liquid droplets entrained in the gas phase during the pre-separation of the Fischer-Tropsch product, lowering the upper limit of the gas phase entrainment rate to 0.4%.

[0161] A comparison of Examples 2-4 with Example 1 shows that, compared to Example 1, in Examples 2-4, the odd-numbered layers of baffles are fixed on the fixed shaft 61 from bottom to top, while the even-numbered layers of baffles are fixed on the inner wall of the gas-liquid phase separator 4, increasing the gas phase path and the contact area of ​​the gas phase in the system. At the same time, a first hydrocyclone 22 and a filter 23 are also provided in the gas phase purification unit 2, further improving the initial separation effect of the gas and liquid phases in the Fischer-Tropsch products, and further reducing the upper limit of the gas phase entrainment rate to 0.2%.

[0162] A comparison between Examples 2-4 shows that, with other structures remaining the same, as the number of water-oil separation sub-units increases (m increases sequentially from 1 to 2 and 3), the oil content in the aqueous phase decreases sequentially, and the water content in the oil phase also decreases sequentially; the oil content in the aqueous phase decreases from 20-60 mg / L to 10-30 mg / L, and then to 0-20 mg / L; the water content in the oil phase decreases from 0-30 mg / L to 0-15 mg / L.

Claims

1. A system for pre-separation of Fischer-Tropsch products, characterized in that, The system includes a gas-liquid phase separation unit (1), a gas phase purification unit (2), and a water-oil phase separation unit (3); wherein, The gas-liquid phase separation unit (1) includes a gas-liquid phase separation tank (4) for feeding Fischer-Tropsch products and separating them into gas and liquid phases, outputting the gas phase from the top to the gas phase purification unit (2) and the liquid phase from the bottom to the water-oil phase separation unit (3). The gas-liquid phase separator (4) is provided with a gas-liquid guide (5) and a baffle assembly (6) arranged coaxially from bottom to top. The gas-liquid guide (5) includes a cylindrical body (51); the bottom surface of the cylindrical body (51) is provided with a feed inlet for feeding Fischer-Tropsch products; the lower part of the cylindrical wall of the cylindrical body (51) is a grid structure for gas-liquid separation of the Fischer-Tropsch products entering it, and the separated liquid phase is guided out from the grid structure to the gas-liquid phase separator (4). The baffle assembly (6) includes a fixed shaft (61) and a baffle (62) coaxially arranged with the cylindrical body (51) for liquid retention of a portion of the gas phase separated from the Fischer-Tropsch products entering the gas-liquid guide (5); The gas phase refining unit (2) includes a cyclone separator (21), which is connected to the gas phase outlet of the gas-liquid phase separation tank (4) in the gas-liquid phase separation unit (1) for receiving the gas phase from the gas-liquid phase separation unit (1) and performing cyclone separation on it, outputting the gas phase from its top and the liquid phase from its bottom. The water-oil phase separation unit (3) includes a water-oil phase separation tank (7), which is connected to the liquid phase outlet of the gas-liquid phase separation unit (1) and the liquid phase outlet of the gas phase purification unit (2) respectively, and is used to receive the liquid phase from the gas-liquid phase separation unit (1) and the liquid phase from the gas phase purification unit (2) and separate them into water and oil. The water-oil phase separation tank (7) is provided with a water-oil separation chamber (8). The bottom surface of the water-oil separation chamber (8) is arranged to decrease sequentially from the feed end wall of the water-oil phase separation tank (7) to its opposite end wall. The feed port of the water-oil separation chamber (8) is connected to the liquid phase outlet of the gas-liquid phase separation unit (1) and the liquid phase outlet of the gas phase purification unit (2) for feeding the liquid phase from the gas-liquid phase separation unit (1) and the liquid phase from the gas phase purification unit (2). The water-oil separation chamber (8) is equipped with an m-stage water-oil separation sub-unit, where m ≥ 1, used to sequentially remove the oil phase from the liquid phase from the feed end to the opposite end; the water-oil separation sub-unit includes a coalescing oil absorption component (81), an oil collection component (82), and an oil conveying component (83); in the m-stage water-oil separation sub-unit, The coalescing oil absorption component (81) is vertically arranged in the water-oil separation chamber (8), and is arranged sequentially from the feed end to the opposite end in the water-oil separation chamber (8), dividing the water-oil separation chamber (8) into m water-oil separation sub-chambers (9) and water chambers (10) arranged sequentially from the feed end to the opposite end. The oil conveying assembly (83) is horizontally positioned at the upper part of the water-oil separation sub-chamber (9) and is used to output the oil phase from the oil collecting assembly (82); The oil collecting component (82) is suspended below the oil conveying component (83) and is flexibly connected to the oil conveying component (83) for floating on the surface of the feed liquid phase; The coalescing oil absorption component (81) is used to output the aqueous phase after the liquid phase has been collected by the oil collection component (82) and the residual oil phase is retained. The water chamber (10) is used to receive the water phase output from the m-stage water-oil separation subunit.

2. The system according to claim 1, characterized in that, In the gas-liquid phase separation unit (1), a first air hole (52) is provided on the top surface of the cylindrical body (51). Multiple first air holes (52) are distributed on the top surface of the cylindrical body (51) to guide and output a portion of the gas separated from the feed Fischer-Tropsch product and to retain the liquid; and / or In the baffle assembly (6), the baffle (62) has n layers, n≥1; the odd-numbered layers of baffles from bottom to top are coaxially and spaced apart on the fixed shaft (61), and a first gap is left between them and the inner wall of the gas-liquid phase separator (4) for use as a gas channel; the even-numbered layers of baffles from bottom to top are coaxially and spaced apart on the inner wall of the gas-liquid phase separator (4), and a second gap is left between them and the fixed shaft for use as a gas channel.

3. The system according to claim 2, characterized in that, A liquid guiding groove is also provided on the surface of the baffle plate (62). The first end of the liquid guiding groove is located on the surface of the baffle plate (62) and the end is located at the edge of the baffle plate (62). It is used to guide the liquid droplets condensed on the baffle plate (62) to the bottom of the gas-liquid phase separator (4).

4. The system according to claim 3, characterized in that, The liquid guiding channel includes a first liquid guiding channel (622), which is disposed from the center to the edge of the baffle (62); and / or The liquid guiding channel includes a second liquid guiding channel (623), the first end of which is located at 1 / 3-2 / 3 of the distance from the center to the edge of the baffle (62).

5. The system according to claim 1, characterized in that, The height-to-diameter ratio of the gas-liquid phase separator (4) is (1.5-4):1; and / or The height ratio of the gas-liquid phase separator (4) to the gas-liquid guide (5) is (1.5-3):1; and / or The diameter ratio of the gas-liquid phase separator (4) to the gas-liquid guide (5) is (1.5-5):

1.

6. The system according to any one of claims 1-5, characterized in that, The oil collection assembly (82) includes a first oil collection assembly (821) in the horizontal direction and a second oil collection assembly (822) in the vertical direction. The first oil collection assembly (821) is horizontally floating on the surface of the feed liquid phase. The two ends of the second oil collection assembly (822) are respectively connected to the first oil collection assembly (821) and the oil conveying assembly (83) for sequentially collecting the oil phase in the feed liquid phase.

7. The system according to claim 6, characterized in that, The bottom surface of the water-oil separation chamber (8) is arranged in a stepped manner from the feed end wall of the water-oil phase separation box (7) to its opposite end wall; wherein, the bottom surfaces of the m water-oil separation sub-chambers (9) and the water chamber (10) are arranged in a stepped manner from the feed end wall of the water-oil phase separation box (7) to its opposite end wall.

8. The system according to claim 7, characterized in that, In two adjacent steps, the step that is behind is higher than the step that is in front.

9. The system according to claim 8, characterized in that, In two adjacent steps, the ratio of the height of the step behind to the height of the step in front is 1-5.

10. The system according to claim 6, characterized in that, In the water-oil separation subunit, the ratio of the length of the second oil collecting component (822) to the vertical length of the coalescing oil absorption component (81) is 10-100%; and / or The thickness of the first oil collection component (821) is 2-50 mm.

11. The system according to any one of claims 1-5 and 7-10, characterized in that, The water-oil phase separation unit (3) also includes an oil tank (11), which is connected to the outlet of the oil conveying assembly (83) and is used to receive the oil phase from the oil conveying assembly (83).

12. The system according to claim 11, characterized in that, The water-oil phase separation unit (3) also includes a second hydrocyclone (12), which is connected to the bottom outlet of the oil tank (11) and is used to extract the water phase deposited at the bottom of the oil tank (11) and separate it by hydrocyclone, outputting the oil phase from the top and the water phase from the bottom.

13. The system according to claim 12, characterized in that, The water-oil phase separation unit (3) also includes an oil suction pump, which is installed on the oil pipeline from the oil conveying assembly (83) to the oil tank (11) and is used to draw the oil phase in the oil conveying assembly (83).

14. The system according to claim 13, characterized in that, The water-oil separation tank (7) is also equipped with an equipment room (13), which is located below the water-oil separation chamber (8). The oil tank (11) and / or the second hydrocyclone (12) are located in the equipment room (13).

15. The system according to any one of claims 1-5, 7-10, and 12-14, characterized in that, The gas-phase purification unit (2) further includes a first hydrocyclone (22) connected to the liquid phase outlet of the cyclone separator (21) for receiving the liquid phase from the cyclone separator (21) and performing hydrocyclone separation on it, outputting the gas phase from its top and the liquid phase from its bottom; and / or The gas phase purification unit (2) further includes a filter (23), which is connected to the gas phase outlet of the cyclone separator (21) and / or the gas phase outlet of the first cyclone separator (22) respectively, for filtering the gas phase from the cyclone separator (21) and / or the gas phase from the first cyclone separator (22) before outputting it.

16. A method for pre-separating Fischer-Tropsch products using the system according to any one of claims 1-15, characterized in that, The method includes the following steps: (1) The Fischer-Tropsch product is transported to the gas-liquid guide (5) in the gas-liquid phase separation unit (1), and is guided out to the gas-liquid phase separation tank (4) through the grid structure on the cylindrical body (51); then the liquid phase entrained in the gas phase is intercepted in sequence by the gas-liquid guide (5) and the baffle assembly (6), and the gas phase is output from the top of the gas-liquid phase separation tank (4), and the liquid phase is output from the bottom of the gas-liquid phase separation tank (4); (2) The gas phase output from the gas-liquid phase separation unit (1) is sent to the gas phase purification unit (2), and cyclone separation is performed by the cyclone separator (21). The gas phase is output from the top and the liquid phase is output from the bottom. (3) The liquid phase output from the gas-liquid phase separation unit (1) and the liquid phase output from the gas phase purification unit (2) are sent to the water-oil phase separation unit (3) and separated into water and oil by the water-oil phase separation box (7), and the water phase and oil phase are output respectively.

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